Giant Planets in Open Clusters S A M U E L Q U I N N G E O R G I A - PowerPoint PPT Presentation

Giant Planets in Open Clusters � S A M U E L Q U I N N � G E O R G I A S TAT E U N I V E R S I T Y � � W I T H � R U S S E L W H I T E ( G S U ) � D AV I D L AT H A M ( C F A ) �

Open clusters are nature’s laboratories � — OCs have long been crucial for testing stellar evolution � — For given age, composition, dynamical environment, can characterize – as function of stellar mass – stellar structure, activity, binary population, etc. � How is planetary formation and evolution affected? � What can we learn from comparative studies? �

But are there any cluster planets to study? � Cluster � Year � Authors � Method � Short period planets* � Hyades � 2004 � Paulson+ � RV � 0 � NGC 7789 � 2005 � Bramich+ � Transit � 0 � NGC 2158 � 2006 � Mochejska+ � Transit � 0 � NGC 7086 � 2006 � Rosvick+ � Transit � 0 � NGC 6791 � 2007 � Montalto+ � Transit � 0 � NGC 188 � 2008 � Mochejska+ � Transit � 0 � Praesepe � 2008 � Pepper+ � Transit � 0 � NGC 2362 � 2008 � Miller+ � Transit � 0 � M37 � 2009 � Hartman+ � Transit � 0 � M67 � 2012 � Pasquini+ � RV � 0 � *2 long period super-Jupiters were known to orbit massive evolved stars in the Hyades (Sato+ 2007) and NGC 2423 (Lovis & Mayor 2007).

Where are the cluster hot Jupiters? � Planets are common around field stars (Fressin+ 2013, Mayor+ 2011). � Most stars form in a clustered environment (Lada 2 2003, Bressert+ 2010). � Shouldn’t we expect planets in clusters? � � Potential explanations: � � 1. Dense stellar environments (like those that survive as clusters) inhibit the formation and/or migration of giant planets. (e.g., Eisner+ 2008). � 2. Given hot Jupiter occurrence around field stars (~1%; Mayor+ 2011, Wright+ 2012), all previous surveys combined might only expect 1 (or 0) planets (van Saders & Gaudi 2011) � But #1 is an important point to keep in mind! � We KNOW the stellar environment affects planets at some level. � Is this a smooth function of environment? Is there a threshold? �

More recent history of cluster planets � Cluster � Year � Authors � Method � Short period planets � Praesepe � 2012 � Quinn+ � RV � 2 � NGC 6811 � 2013 � Meibom+ � Transit � 2 (mini-Neptunes) � Hyades � 2014 � Quinn+ � RV � 1 � M67 � 2014 � Brucalassi+ � RV � 2 � Adjusted for completeness: � Field stars: � ~ 1% � + 1.92 % 1.97 − 1.07 Praesepe and Hyades: � + 0.96 % [Fe/H]=0 equivalent: � 0.99 − 0.54 � + 3.00 % 2.00 − 1.50 M67: � � NGC 6811: consistent �

The Planetary Laboratory � Example experiment: Does hot Jupiter migration occur primarily through interactions with the disk (Type II) or with other bodies (planet-planet scattering, Kozai-Lidov)? � Planet-planet scattering � Type II � P. Armitage � Ford & Rasio; T. Schindler/NSF � — Expected to preserve circular orbits � — Can produce significant eccentricity � — Occurs within 10 Myr � — May take hundreds of Myr � Observing soon after migration can identify dominant mechanism �

Case Study: HD 285507b � 300 Eccentricity could be indicative of: � Radial Velocity (m s -1 ) — the mode of migration � 200 — ongoing dynamical interaction � 100 — a recent encounter � + 0.018 e = 0.086 − 0.019 0 Hyades t age = 625 Myr � 30 O-C 0 0 � -30 0.0 0.2 0.4 0.6 0.8 1.0 Circularization timescale is roughly: � Orbital Phase − 1.5 − 5 " % 6.5 " % " % " % " % t cir = 1.6 Gyr × Q P M P M * × R P a ≈ 11.8 Gyr '× $ '× ' × $ ' $ ' $ $ ' $ 10 6 M Jup M Sun R J 0.05 AU # & # & # & # & # & (Adams & Laughlin 2006) � We call HD 285507b “dynamically young” ( t age < t cir ); it may have migrated via planet-planet scattering or Kozai cycles �

Dynamically young hot Jupiters are eccentric � >0.16 0.15 1.0 “Dynamically old” � 0.14 0.13 0.12 0.5 0.11 log(t age ) (Gyr) 0.10 0.09 0.08 0.0 0.07 0.06 0.05 -0.5 0.04 6 4 0 0 1 1 6 0.03 x x 0 2 1 6 = = = 0.02 “Dynamically young” � P P P Q Q Q 0.01 -1.0 K-S test: samples come from 0.00 -4 -2 0 2 different parent distributions log( τ cir ) (Gyr) with 99.997% confidence �

A constraint on the tidal quality factor Q P � >0.16 0.15 1.0 0.14 10 -2 0.13 0.12 0.5 0.11 KS Probability log(t age ) (Gyr) 0.10 10 -3 0.09 0.08 0.0 0.07 0.06 10 -4 0.05 -0.5 0.04 Q P = 2 x 10 6 Q P = 6 x 10 4 Q P = 10 6 0.03 0.02 10 -5 0.01 -1.0 0.00 10 5 10 6 10 7 -4 -2 0 2 Q P log( τ cir ) (Gyr) — Changing Q P changes the two samples � — A K-S test for each new Q P quantifies the difference � — The most significant difference should occur for the true Q P value – that is, when we have divided the dynamically young and old samples in the correct place �

A constraint on the tidal quality factor Q P � 10 -2 KS Probability 10 -3 10 -4 Jupiter-Io constraint (Yoder & Peale 1981) � + 0.41 Quinn et al. 2014 � log Q P = 6.14 − 0.25 10 -5 10 5 10 6 10 7 Q P

OC Lab Experiments: Migration Timescales � — Younger planets constrain migration via required timescale � ¡ Hot Jupiters orbiting T Tauri stars would prove Type II can work � ¡ Hot Jupiter frequency should change with age, dependent upon the importance of each mechanism � PTFO 8-85961 is a candidate hot Jupiter orbiting a T Tauri star (van Eyken+ 2012, Barnes+ 2013), though it has been called into question with further observation (Yu+ 2015). � Barnes+ 2013 �

OC Lab Experiments: System Architecture � — Presence of long period giant planets can: � ¡ Provide “smoking gun” evidence for migration of an inner planet � 500 300 300 -350 400 Radial Velocity (m s -1 ) Radial Velocity (m s -1 ) Radial Velocity (m s -1 ) Radial Velocity (m s -1 ) 200 200 300 100 -400 200 100 0 100 -450 -100 0 0 -200 -100 -100 -500 60 40 90 90 35 20 O-C O-C O-C O-C 0 0 0 0 0 0 0 -20 -90 -90 -35 -40 -60 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 1400 1600 1800 2000 2200 Orbital Phase Orbital Phase Orbital Phase BJD (-2455000) A system of 44-day and 500(?)-day A 90-day Jupiter with an outer massive planets in Coma Berenices. � companion (likely stellar), in Coma Ber. �

OC Lab Experiments: System Architecture � — Presence of long period giant planets can: � ¡ Map planetary system structure as a function of environment � 200 200 Radial Velocity (m s -1 ) Radial Velocity (m s -1 ) Radial Velocity (m s -1 ) 100 100 100 50 0 -100 0 0 -200 -100 100 80 100 60 50 50 40 O-C O-C O-C 20 0 0 0 -20 -50 -50 -40 -100 -100 1000 1200 1400 1600 1800 2000 2200 1000 1200 1400 1600 1800 2000 2200 1000 1200 1400 1600 1800 2000 2200 BJD (-2455000) BJD (-2455000) BJD-2450000 Orbits (and survival) of terrestrial planets are shaped by their giant counterparts. Do long-period Jupiters also have occurrence at similar rates in clusters and the field? �

OC Lab Experiments: System Architecture � — Presence of long period giant planets can: � ¡ Directly connect RV and directly imaged populations � 1.00 1.00 Adolescent OCs are a sweet spot for RVs + direct imaging. � Companion mass (M Sun ) Companion mass (M Sun ) � Very young stars rotate too rapidly with too much activity for RVs. � 0.10 0.10 � Older substellar companions are hard to directly image. � � Coma Ber This allows characterization of 0.01 0.01 RV AO+NRM substellar companions at all separations around a single population 1 1 10 10 100 100 of well-characterized stars. � Separation (AU) Separation (AU)

Summary: OCs as Exoplanet Laboratories � — Controlled for age, composition, dynamical environment � ¡ planet-stellar mass dependence, planet-metallicity dependence, etc. � — Occurrence and orbits as function of age constrain migration � ¡ plus, additional benefits like the constraint on Q P � — Benchmark transiting systems (precise stellar and planetary properties) � — Direct imaging of wide giants/brown dwarfs for formation/evolution � ¡ well-characterized stars, especially age, enable better model comparison � — Observationally connect populations of wide imaged companions and RV planets � — With K2 and TESS, the OC opportunity extends to small planets � — OCs represent limits on the environmental influence on planet formation – do architectures of planetary systems (including small planets!) change in the densest stellar environments? � — And more! �